Evaluating the capacity of land to shelter growing human activity without sacrificing their quality and source of life

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Tuesday, March 7, 2017

Graduating from the Floor Area Ratio - revised

The floor area ratio FAR is a zoning regulation originally
created to protect public health, safety, and welfare from excessive
construction in urban areas. It is a project measurement equal to gross
building area divided by gross land area in square feet. A floor area ratio of
5, for instance, means that 5 acres of gross building area may be constructed
on one acre of gross land area. The simplicity of the regulation is attractive,
but its simplicity inadequately leads the decisions that combine to determine
shelter capacity, intensity, intrusion, and dominance within projects,
neighborhoods, districts, cities, and regions.

CORRELATION

I’ll make my point with Table 1. It is a forecast model
constructed to predict shelter capacity in square feet of gross building area
per buildable acre of land when no parking is required. There are eight boxes
in the Land Module and five boxes in the NPL Module. The values entered in
these boxes may be modified at will and represent design specification
decisions. These decisions are correlated to find the maximum core area
available for a building floor plan in cell G32 using the architectural
algorithm in cells H3-H33. The core area found in cell G32 is used by the
master equation in cell A35 to predict gross building area options in cells
B40-B49. These options are based on the floor quantity alternatives entered in
cells A40-A49.

The shelter capacity options related to the gross building
area predictions in Col. B of the Planning Forecast Panel are calculated in cells
D40-D49 using the equation in cell D39. Shelter capacity is expressed in building
sq. ft. per acre.

Massing ratios related to the gross building area options in
Col. B of the Planning Forecast Panel are calculated in Col. E. These ratios
are used by the equation in cell F39 to calculate the intensity represented by
each gross building area option in Col. B of the Planning Forecast Panel.

Related intrusion measurements are calculated in Col. G. They
are used to calculate dominance options in Col. J of the Planning Forecast
Panel using the equation in cell H39.

Finally, the floor area ratio representing each gross
building area option in Col. B of the Planning Forecast Panel is calculated in
Col. J using the equation in cell J39.

The point is that the floor area ratios calculated in Col. J
of the Planning Forecast Panel react to the specification decisions entered in
the 23 boxes of the NPL forecast model. The floor area ratio does not lead them,
and our emphasis on the ratio as a leadership tool has produced confusion, argument,
conflict, and the application of legal opinion based on the precedent of
mistaken assumptions. I’ll make my point with one issue.

In my opinion, the most significant topic omitted from floor
area regulation is the provision of social open space for people at street
level. The opposing argument has contended that social open space is a public
benefit that should be purchased at public expense. The open space specification
in cell F11 of Table 1 is zero percent in cell F11 to begin an evaluation of
these two positions. The value represents a developer’s attempt to maximize leasable
building area on a given, high-cost urban land area. If the floor area ratio
limit for Table 1 is 19, the design specification predicts that a 20 story
building will produce 823,776 sq. ft. of gross building area and a floor area
ratio of 18.91. I could have adjusted the specification values to make the
floor area ratio exactly 19 in cell J47, but left it so I could point out that predictions
will change whenever one or more specification values are modified in Table 1.

Table 2 has revised the zero percent value in cell F11 of
Table 1 to 32.18%. All other specification values from Table 1 are held
constant in Table 2. The 32.18 percentage has been entered to make the floor
area ratio in cell J49 of Table 2 identical to that in cell J47 of Table 1. A
comparison shows that the same floor area ratio and gross building area can be
achieved when 32.18% of open space is provided for pedestrian relief at street
level, but the trade-off is an increase from 20 stories in Table 1 to 30
stories in Table 2. The additional stories represent additional cost to reach
an equal gross building area. In the past an increase in height was considered
a bonus in return for social open space at the pedestrian level, but the
calculations in Table 2 show that ten additional floors produce gross building
area parity.

It could be argued that a bonus would involve negotiations for
building height in excess of ten stories to compensate for the cost of
increased building height. It could just as easily be argued that the floor
area ratio of 16 was a reasonable limit; that social open space has been
ignored as an essential part of the effort to protect public health, safety,
and welfare within urban pattern and form; and that the deficiency should not
be allowed to continue. I do not intend to resolve the argument. I only wish to
point that it can be debated on a more credible foundation of measurement,
evaluation, prediction, and knowledge. Cooperation between public and private
interest will not be secured until all parties can sit around a table
discussing options with a common language that can accurately predict
implications.

GROSS
BLDG AREA

In most cases a developer will know the land area involved,
but in some cases he or she will be exploring the buildable land area needed to
serve a given gross building area objective when a floor area ratio is given. Table
3 has been constructed to answer this question. If a floor area ratio of 16, a
gross building area objective of 850,000 sq. ft. and a 30% social open space
objective are given in addition to the other specification values noted, the
master equation in cell A36 and the secondary equations in row 40 of the
Planning Forecast Panel predict that 1.212 buildable acres will produce a floor
area ratio of 16.10 in cell K49 when a 25 story building is chosen in cell A49.
A slight modification to the specification values entered in the NPB Module of
Table 3 could reduce 16.10 to a precise floor area ratio value of 16 in cell
K49. The entire specification would represent a public/private agreement.

Table 4 shows that when no open space is provided in cell
F10, the same gross building objective and floor area ratio can be reached on
the same land area with only 17.5 building floors. The floors needed to
compensate for the 30% public open space dedication in Table 3 would be a
subject for negotiation as mentioned previously.

CONCLUSION

When social open space was introduced in Tables 2 and 3, the
intensity and dominance calculations in columns F and H of the Planning
Forecast Panel dropped from those calculated in Tables 1 and 4. There is no
research that defines acceptable levels of intensity and dominance, but the
ability to measure these conditions brings us closer to the knowledge needed to
protect public welfare and improve quality of life within urban areas.

At the present time, most cities are woven together with
ribbons of sidewalk and torrents of traffic. In the most extreme cases, these
rivers flow between canyons of artificial stone and glass governed by skyplane
regulations that attempt to ensure light, air, and ventilation penetrate to
street level. In other cases, the sidewalk is omitted and replaced by a parking
lot that qualifies as a front yard. In both cases, it has been our method of
protecting the public health, safety, and welfare with minimum standards that
are now coming into question. Why is the public being protected with government
standards meant to keep them alive with a minimum quality of life (welfare)? The
measurements of shelter capacity, intensity, intrusion, and dominance in Tables
1-3 represent a method of calibrating “welfare” so that research can begin to produce
the knowledge needed to define minimum standards for livable cities.

The physical intensity, intrusion, and dominance of shelter,
movement and life support within cities is offset by social open space. The
result is referred to as urban form composition. We have yet to write the first
score in this composition with a language that can lead the orchestra. The
result has been discordant practice as virtuosos independently tune their
instruments.

The first step is to recognize that a language is needed.
The second is to recognize that cities must be woven together with social open
space before they can begin to protect a population’s physical, social,
psychological, environmental, and economic welfare.

Tables 1-3 were included to illustrate how open space
negotiations can begin when assumptions are replaced with accurate measurement
and calculation. The debate concerns the need for this open space to protect
the public welfare, and the public/private share of this expense. These are
political questions that require additional knowledge, and I do believe that
answers are needed. The Science of City Design[1]
has been written to encourage you to explore these questions with a credible
language. It can lead us to a geographically limited Built Domain capable of
protecting our quality and source of life -- the Natural Domain.

[1]
Hosack, Walter M., The Science of City Design, CreateSpace, 2016. (Available
in paperback and e-book versions from Amazon.com)

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About Me

Walter Hosack has leadership, management, design, and production experience in city planning, urban design, architecture, civil engineering, building regulation, code compliance, and zoning administration. He is a retired registered architect, certified city planner, and government official. He has been a past member of the AIA, AICP, and NCARB. Over the past 40 years, he has planned, designed, produced, and managed projects ranging in size from residential homes to $100 million commercial and institutional projects.
He is the author of "Land Development Calculations" and attached software entitled, "Development Capacity Evaluation" published by The McGraw-Hill Companies, New York, NY, 2001, second edition 2010. The first edition was translated and published by The China Electric Power Press, Beijing, China in 2007.
The "Science of City Design" is his latest effort and was released in July, 2016.
These books can be found at: https://www.amazon.com/-/e/B001IR3ODO?ref_=pe_584750_33951330
Mr. Hosack holds Bachelors and Masters Degrees in Architecture and City Design from Miami University, Oxford, Ohio.